’s Ship Laboratory has developed a computer program for transit simulation
along the Northern Sea Route as well as any other ice covered navigation route. The
program is capable of predicting the average speed and propulsion energy
consumed for any ship and a variety of ice conditions on the basis of certain ship
parameters (e.g. length between perpendiculars, beam, propeller diameter, etc.)
and quantities describing the ice cover (e.g. level ice thickness, ridge
density, etc.). The basis for the calculations is the determination of the vessel
speed by equating net thrust available to total ice resistance. The program can
simulate navigation of a ship in a navigation channel, in level ice, in ridged
ice and in a floe ice field. For the ridged ice and floe ice fields probability
distributions are used to model the spacing and size of floes and ridges. This
results in statistically distributed vessel speeds for the same set of
parameters used to describe these two fields. Verification of the routine was performed
using the limited data available about ship performance in level ice, floe ice
and one ridged ice case.

The program was used to investigate the effect of variations in ice conditions
on the average speed of the vessel. Level ice thickness, mean channel ice
depth, ridge sail height and density and floe size and coverage were the studied
parameters describing the ice conditions. For this sensitivity analysis a SA-15
series ship was used.